Sociality and tattoo skin disease among bottlenose dolphins in Shark Bay, Australia

Social behavior is an important driver of infection dynamics, though
identifying the social interactions that foster infectious disease
transmission is challenging. Here we examine how social behavior impacts
disease transmission in Indo-Pacific bottlenose dolphins (Tursiops
aduncus) using an easily identifiable skin disease and social network
data. We analyzed tattoo skin disease (TSD) lesions based on photographs
collected as part of a 34-year longitudinal study in relation to the
sociality of T. aduncus using three metrics (degree, time spent
socializing, and time in groups) and network structure, using the k-test.
We show that calves with TSD in the second year of life associated more
with TSD-positive individuals in the first year of life compared with
calves that did not have TSD. Additionally, the network k-test showed that
the social network links are epidemiologically relevant for transmission.
However, degree, time spent in groups, and time spent socializing were not
significantly different between infected and uninfected groups. Our
findings indicate that association with infected individuals is predictive
of an individual’s risk for TSD and that the social association network
can serve as a proxy for studying the epidemiology of skin diseases in
bottlenose dolphins.